The intention of the new privacy feature is to shield your phone from being identified as it probes for wifi signals that it can use to hook up to the internet or use to service its apps. (If you’ve ever left your wifi on and later discovered a long list of strange wifi services that your phone has tried to hook up to, this is what we’re talking about.)

The problem is that your iPhone needs to be in these three conditions for the phone to actually be anonymous to other people’s wifi, according to AirTight:

Wifi must be on but not hooked up to an actual wifi service.

Phone needs to be in sleep mode.

Location services need to be OFF in the privacy settings.

Needless to say, almost nobody keeps their phone this way. Many of the most popular apps won’t even work if you have location services off, and it’s pointless if the protection ends as soon as you wake up your phone. An AirTight spokesperson told Business Insider that perhaps 99% of users won’t be protected by the MAC randomization in iOS 8.